Breathing mask



FIG. 1 is a perspective view of a breathing mask according to our design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines showing environment or structure of the breathing mask are for illustrative purposes only and form no part of the claimed design.

The stippling represents a contrast in material. 

CLAIM The ornamental design for a breathing mask, as shown and described. 